群落演替对呼伦贝尔草地两种优势植物繁殖分配及生态化学计量的影响

为了探究草地群落演替过程中不同优势种的生理生态适应性,本研究采用空间代替时间序列的方法,分析呼伦贝尔草地米氏冰草群落—米氏冰草+冰草群落—冰草群落演替系列的土壤养分、两优势种的生物量及C、N和P含量。结果表明: 随着米氏冰草群落—米氏冰草+冰草群落—冰草群落的演替,土壤全碳、全氮、速效氮及速效磷含量均显著升高;米氏冰草和冰草叶、茎和根的N、P含量及N/P均显著升高,而各构件的C/N降低;米氏冰草叶的C含量及冰草叶、茎和根的C含量均显著升高。米氏冰草叶C/P及冰草根和叶C/P均显著升高,而米氏冰草根和茎C/P及冰草茎C/P均显著下降。在米氏冰草+冰草共优势种群落中,米氏冰草通过降低茎和根C含量,增加叶C的积累,提高其种间竞争力, 而冰草通过降低根冠比和生殖比来适应环境变化。米氏冰草在不同群落中均受N限制(N/P<14);而冰草在单优势种群落中受P限制(N/P>16),在共优势种群落中受N和P限制(14

Effects of community succession on plant reproductive allocation and ecological stoichiometry for two dominant species in the Hulunbuir Grassland,China

To explore the physiological and ecological adaptability of different dominant species during grassland community succession, we measured soil nutrients, plant biomass and C, N and P contents of two dominant species using the method of spatial sequences instead of chronosequences in the successive series of Agropyron michnoi community - A. michnoi + A. cristatam community - A. cristatam community in Hulunbuir Grassland. During the succession progress, the contents of soil total C, total C, available N and available P increased significantly. The N and P contents and N/P of leaves, stems and roots of A. michnoi and A. cristatam increased significantly, while the C/N showed opposite response. The leaf C content of A. michnoi and the C contents of leaves, stems and roots of A. cristatam significantly increased. The leaf C/P of A. michnoi and the C/P of leaves and roots of A. cristatem increased significantly, while the C/P of stems and roots of A. michnoi and the stem C/P of A. cristatem decreased significantly. In the community co-dominated by A. michnoi and A. cristatam, A. michnoi improved its interspecific competitiveness by reducing C content in stems and roots and increasing the C content in leaves, while A. cristatem adapted to environmental changes by reducing root to shoot ratio and reproductive ratio. A. michnoi was limited by N availability (N/P<14) in different communities, while A. cristatem was limited by P availability in single dominant community(N/P>16)and by both N and P in co-dominant community (14A. michnoi in the single dominant community and the co-dominant community were 5.92 and 2.94, respectively, indicating higher N stability, while the index of stoichiometric homoeostasis plant of foliar P of A. cristatem in the single dominant community and the co-dominant community were 4.12 and 3.37, respectively, which indicated higher P stability.